1. Field of the Invention
This invention relates to a method of preventing adhesion of scales in city water or in circulating water at some portion or around an inner periphery of a water pipe, and more particularly to a method of preventing adhesion of scales in city water or in circulating water such as in a cooling system, a boiler or a heat exchanger at some portion or around an inner periphery of a water pipe, whereby maintenance is eased, circulating water can be maintained normally with a minimum flow in a water pipe and service water can be effectively used.
2. Description of the Prior Art
It has been reported that when industrial water in a device such as a cooling system is passed through a magnetic field, scales are prevented from being produced in the industrial water as shown in the published specifications (not examined) of the Japanese Patent Publication No. 112115/1977, 118187/86 and the Utility Model Publication No. 108156/1983.
More particularly, it is described in the specification of the Japanese Patent Publication No. 112115/1977 that the magnetic field is applied by a permanent magnet into a circulating liquid, oil or liquefied gas in a pipe in order to prevent production of scale or sludge.
It is also mentioned in the specification of the Japanese Patent Publication No. 118187/86 that a device for magnetically treating a material is used to prevent adhesion of mineral such as calcium, silica or magnesium onto an inner periphery of a pipe.
A device for magnetically treating a liquid in a pipe is also described in the specification of the Japanese Utility Model Publication No. 108156/1983.
It is described in the foregoing specifications that undissoluble impurities in water are ionized by a permanent magnet or an electromagnet to promote dissolution of the impurities so that an effect of preventing scales from being produced in water is proportional to a strength of the magnetic field.
In addition, according to Japanese standard for cooling water of air conditioning and refrigerating equipment, it has been reported that scale adhesion is mainly caused in a solution having a calcium carbonate content (hardness) over 200 ppm and a silicic acid content over 50 ppm. But a process for treating the solution containing comparatively undissoluble substance has not been found.
3. Disadvantages of the Prior Art
According to the conventional device having a magnetic treatment equipment, however, in which water is passed through the magnetic field, the strength of the magnetic field is restricted by the diameter of piping for mounting the magnet. In addition, the device for circulating water around the magnet is very complicated, and the circulating speed of water cannot be increased so that an effective magnetic treatment of water is difficult.
In consequence, it is preferable to provide an electro-magnet having a magnetic flux density of more than 8000 Gs., but it is very difficult to make such an electro-magnet having such a high magnetic flux density, thus making it impossible to use it as an industrial product practically.
The electro-magnet having less than 8000 Gs. has been experimentally made, but such an electro-magnet has not been found to have the suitable magnetic flux density for preventing generation of scales in water and its magnetic field dependency in accordance with the kind of ions has not been confirmed.
The present inventors have been working on the subject for many years, and have discovered that a compact electro-magnet having a strong magnetic flux density of more than 8000 Gs. has an extraordinary effect of preventing adhesion of scales, depending upon the kind of ions.
As indicated above, according to Japanese standard for cooling water of air conditioning and refrigerating equipment, adhesion of scales highly occurs in a solution containing a calcium carbonate content (hardness) over 200 ppm and a silicic acid content over 50 ppm. The method of this invention is very effective for treating such a solution containing such substances which cause adhesion of scales.